Systems and methods herein generally relate to machines having print engines such as printers and/or copier devices and, more particularly, to printer color management in image/text printing or display systems.
The color gamut of a printer is a multi-dimensional space of a given volume with the axes of the space being set or defined initially by the pigments used in the colorants of the primary colors. Each set of color primaries: red, green, blue (RGB) or cyan, magenta, yellow, and black (CMYK), defines a “color space” that includes all colors that can result from any combination of these primaries. The “color space,” or “color gamut,” may be quite different for different sets of primaries. In forming multi-color output images on an image-receiving medium, each of the primary colors is transferred to the image-receiving medium in turn. The color gamut is defined by the interaction of the primary colors, and is limited by a total amount of colorant in any combination that can be effectively deposited on the image-receiving medium. In other words, it is not possible to print some colors that can be photographed or displayed on a monitor when using CMYK printing. The color gamut for a particular image forming device and an associated color rendition dictionary (CRD) by which images may be produced by the image forming device is usually stored in metadata with the image forming device. The CRD and associated set of set points programmed into the image forming device, or family of image forming devices, ensures that the color gamut produced by that image forming device covers an available standard color spectrum. Typically then, image forming devices are delivered with a single CRD available in the image production system.
In multi ink applications additional color inks are added to extend gamut. In such cases, there are typically colors that are complimentary; that is, they have hue angles that are roughly 180 degrees apart. This is typical since these additional colors are used to extend the 4-color gamut and to produce a color that is outside those reachable using solely CMYK. For example, typical secondary colors, such as a deep red (complementary to cyan), which is a combination of magenta and yellow, are very hard to reach. The same if often true of green (complementary to magenta) and blue (complementary to yellow). For complementary colors, the presence of both colors tends to produce a neutral hue, so it is not necessary for gamut extension, the primary use of these additional colors, to use the complementary inks simultaneously; complementary inks, therefore, tend be used mutually exclusive of each other. The mutual exclusiveness of the complementary ink pairs is a loose restriction. There are areas of color space where both inks might be present as the color management transitions from use of one ink to the other. However, both inks are not significantly present at the same time.